#include <iostream>
class Test
{
public:
    Test(int a, int b) : m_a(a), b(b)
    {
    }
    void show()
    {
        std::cout << m_a << std::endl;
    }

private:
    const int m_a;
    int b;
};
int main()
{ 
    Test t(10, 20);
    t.show();
}